Manufacture of artificial filaments, threads, and the like

ABSTRACT

Hollow artificial silk &amp;c. of more or less low lustre is made by the dry spinning method by applying a precipitant to the filaments at an early stage of their drying, and subsequently producing a rapid evaporation of the solvent.  The precipitant which is preferably applied to the filaments immediately on extrusion, may be employed in the form of vapour, but is preferably employed as a liquid; and it may be applied as a spray either to the filaments or to the spinning nozzle, or carried by the additional evaporative medium injected into the region of the spinning nozzles according to the methods of Specifications 325,233, [Class 2 (ii), Cellulose &amp;c.], and 341,075, or the liquid precipitant may be applied as a film to the spinning nozzle according to the method of Specification 371,360, the spinning being carried out either downwardly or upwardly.  The necessary rapid evaporation of the solvent may be produced by means of heating devices grouped below the point of application of the precipitant, or by increasing the rate of flow of the evaporative medium at this point as by the use of the collector devices of Specifications 300,998, 304,674, and 326,232, [all in Class 2 (ii), Cellulose &amp;c.]. The method is particularly applicable for the production of filaments &amp;c. from solutions of cellulose acetate and other organic esters of cellulose, and of cellulose ethers.  Precipitants that may be used with acetone-soluble cellulose acetate are alcohols such as ethyl and amyl alcohols, esters such as butyl acetate and propionate, and ethers such as dipropyl ether, but it is preferred to employ liquids of very high precipitating power such as benzene, toluene, xylene and other cyclic hydrocarbons, and aliphatic hydrocarbons, for example, petroleum fractions boiling between 60 and 120 DEG  C.; the action of the precipitant is improved in some cases by the addition of water thereto or to the spinning solution, or the precipitant may be added to the spinning solution.  It is preferred to employ a precipitant which is less volatile than the solvent of the spinning solution, and in producing the rapid evaporation of the solvent to employ temperatures above its boiling-point but below the boiling-point of the precipitant.  The filaments may be improved in strength or their lustre may be modified by treatment either continuously with their manufacture or otherwise, according, for example, to the processes of Specifications 277,089, 323,790 and 336,217, [all in Class 2 (ii), Cellulose &amp;c.], the filaments being stretched with or without the application of solvents or swelling agents which may be derived from the spinning solution or may be incorporated in the precipitant liquid.  The spinning solutions may contain substances that modify the lustre of the filaments, for example, the substances specified in Specifications 338,490, [Class 2 (ii), Cellulose &amp;c.], 341,897, 343,949, 346,678 and 346,793. Specifications 314,404, 327,740, [both in Class 2 (ii), Cellulose &amp;c.], 355,652, and 355,720 also are referred to.

March 3; 1936. H. DREYFUS 2,032,565

MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS AND LIKE Fild Jan. '7, 1952 FIQL FIQ Z Patented Mar. 3, 1936 PATENT OFFICE MANUFACTURE OF ARTIFICIAL FILA- MEN'I'S, THREADS, AND THE LIKE Henry Dreyfus, London, England Application January 7, 1932, Serial No. 585,380 In Great Britain February 19, 1931 11 Claims.

This invention relates to the production of artificial filaments, threads or the like from solutions of cellulose acetate or other cellulose derivatives by dry spinning methods, and is more particularly concerned with the production of filaments,

threads or the like having a more or less voluminous or hollow structure and being more or less of low lustre.

In U. S. Patent No. 1,943,353 and British Patent No. 355,652, processes are described in which filaments, threads or the like are produced by the dry spinning or evaporative process and in which a liquid is applied to the filaments during their drying, and particularly at an early stage 5 thereof, U. S. Patent No. 1,943,353 being more particularly concerned with obtaining an increase or decrease in the lustre of the filaments or other products due to such application of liquid. Again U. S. Patent No. 1,959,443, describes inter alia 1:0 the production of filaments or threads of reduced lustre by spinning solutions of cellulose acetate or other organic esters or ethers of cellulose into an evaporative atmosphere containing organic precipitants for the cellulose derivative so as to exert a precipitating action upon the cellulose derivative while the filaments are being formed.

I have found that hollow or voluminous filaments or other products may be produced by applying to the filaments or the like a precipitant for the base of the spinning solution in an early stage of the drying of the filaments or other products, and preferably immediately upon their extrusion from the spinning nozzle, and thereafter promoting a rapid evaporation of the solvent 7 contained in the filaments or like products. The

precipitant may be applied in the form of a vapour, but is preferably applied as a liquid. I have found in fact that such precipitants may cause a skin to be formed upon the filaments or other products and that upon further evaporation of the solvent contained in the more or less liquid filaments or threads a hollow or voluminous structure develops in the filament.

In U. S. Patent No. 1,943,353 it is indicated that the precipitant, for example xylene, may be applied at a distance of some 4 to 8 inches from the spinning nozzle, while in U. S. Patent No. 1,959,443, in Example 1, petrol vapour is injected into the evaporative medium at a distance of some 3 inches from the nozzle. In the process of the present invention it is preferable to apply the precipitant much closer to the nozzle than is indicated in the examples of these prior specifications, and most advantageously the precipitant is applied to the filaments at the moment that they are extruded from the nozzle. This may be achieved in a number of difierent ways.

The precipitant may for example be sprayed in the liquid state on to the filaments immediately they are extruded from the nozzle, or the nozzle face itself may be sprayed with the precipitant. In employing such spraying methods a suitable atomizer may be employed. For example a stream of petrol or other precipitant may be carried into the path of the additional evaporative medium injected into the region of the spinning nozzles, according to U. S. Patent No. 1,934,618 and British Patent No. 341,075, the additional evaporative medium being applied either inside the ring of filaments in the case of using a ring type jet or outside or both.

Another means of applying a precipitant in the liquid state at the moment of the formation of the filaments or other products is that described in British Patent No. 371,360. According to this method the spinning solution is extruded from the nozzle directly into a layer of liquid insufficient in quantity to cause the filaments to cling together. In one method of carrying out this process the under side of a spinning nozzle adapted to spin downwards, though not necessarily vertically downwards, is covered and continuously supplied with an adhering film of coagulant. The film of coagulant, before spinning commences, completely covers the extrusion orifices of the nozzle, and when spinning is started the filaments falling or being drawn through the film of coagulant carry with them a small quantity of the liquid. Conveniently the jet orifices may be formed at the centre or towards the centre, say in a ring round the centre, of a hemispherical nozzle, the upper edge of the hemispherical nozzle being flanged to fit into a cup-shaped member supplied with coagulant. The cup-shaped member may, for example, be notched at intervals round its circumference, so as to permit the coagulant to fiow slowly in the form of a film round the entire outside surface of the hemispherical nozzle. Preferably the rate at which the coagulant is supplied to the outside surface of the nozzle dur-. ing spinning is adjusted so that the film of coagulant does not tend toform in drops over the jet orifices or in other words the filaments are extruded at a sufficient rate to carry away the whole of the coagulant sup-plied. It will thus be seenv that the filaments are formed in a body of coagulant, and in this preferred form they carry this coagulant as a kind of sheath or outside layer for some distance during their travel. They may then be treated according to dry spinning proc-i.

esses so as to evaporate the solvent from the spinning solution and also to evaporate the coagulant supplied to the nozzle.

The above method of carrying the invention into effect consists in bringing a body of coagulant from the outside towards the ring of spinning jets or orifices. The invention is not of course limited to such an arrangement of the jet orifices or to such a means of bringing the coagulant thereto. For example the jet orifices may be spread over a substantially flat surface or over a surface of any convenient shape, but preferably they are so arranged that substantially equal amounts of coagulant are capable of contacting with each of the filaments in the moment of their formation. Another method of carrying the invention into effect consists in supplying coagulant to the inside of a ring of jet orifices, so as to cover the nozzle face with a film as before. Or again a coagulant may be supplied both from the inside and outside of a ring of orifices. Further the orifices may be arranged in line along a wedge-shaped jet, i. e. a jet of more or less triangular cross-section. The coagulant may then be caused to flow in the form of a film down the outside of the two faces of the wedge towards the edge along which the jet orifices are arranged. A similar arrangement may be adopted in the case of a single line or a plurality of lines or orifices arranged in a nozzle having a semicylindrical shape. The ring-shaped nozzles described in British Patent No. 355,720 may be considered to be jets of this type and are very suitable for use in the present invention. The coagulant may be supplied to the interior of the circular line of jets by way of the recessed portion of the nozzle or more advantageously to both the exterior and the interior of the jets.

A further means of carrying the invention into effect consists in continuously supplying with a film of the coagulant the upper surface of a spinning nozzle adapted to spin upwardly. The nozzle may for example be planar or concave or even convex. In the last case the coagulant may be supplied to the centre of the jet and in the first case either to the outside or to the centre or both, while it is most convenient in the case of a concave jet to supply the coagulant from the exterior edges of the jet. As in the case of downward spinning, line jets may be used and suitable methods of supplying the coagulant will be obvious from the above description.

After producing a precipitation of the cellulose derivative in the filaments or other products the latter are thereafter treated to obtain a rapid evaporation of the solvent still contained in the filaments. To this end suitable heating devices may be grouped below the point of application of the coagulant, or alternatively an increased evaporation may be obtained by increasing the rate of flow of the evaporative medium in the desired neighbourhood, as for example by means of the collector devices described in U. S. Patents Nos. 1,814,468 and 1,942,540 and British Patent No. 304,674. If desired these two methods of producing a rapid evaporation may be combined, as for example by providing the collector devices with heating arrangements, as described in U. S. Patent No. 1,814,468. By reason of the evaporation of the solvent still contained in the filaments or other products and the previous precipitation of part of the cellulose derivative contained in the spinning solution hollow spaces or lumens develop within the filaments.

The process of the present invention may be may for instance be stretched either discontin- {is applied to the production of filaments, threads or the like from solutions of any suitable substances capable of being spun by the dry spinning method, for example cellulose acetate, or other organic esters of cellulose, e. g. cellulose formate, cellulose propionate, or cellulose butyrate, cellulose ethers, for example ethyl, methyl or benzyl celluloses or cellulose nitrate. The precipitant for use in the process will of course be chosen in accordance with the nature of the cellulose derivative employed in the spinning solution. As examples of suitable precipitants for acetone soluble cellulose acetate, the alcohols, for instance ethyl alcohol, amyl alcohol and the like, and esters, for example butyl acetate and propionate or ethers, for instance di-propyl ether, may be mentioned, but I prefer to employ liquids which have a Very high precipitating action upon the cellulose derivative, and particularly hydrocarbons, for example the cyclic hy-' drocarbons, including benzene and its homologues, such as toluene and the Xylenes, and also the aliphatic hydrocarbons, for example the various fractions of petroleum, preferably those boiling between 60 and 120 C. I prefer to employ organic coagulants, but I find that in some cases the action of the organic coagulant is improved either by admixture of water therewith or by incorporation of water in the spinning solution itself. Further I may, according to the present invention, incorporate in the spinning solution coagulants other than water, for examplc the various organic coaguiants listed above.

It is preferable in working the process of the present invention to employ a coagulant which is less volatile under the spinning conditions than is the solvent or solvent mixture of the spinning solution. On the other hand it may be sufficiently volatile to be completely or substantially eliminated from the filaments during the actual spinning process. It is most convenient in order to produce the rapid evaporation of the solvent after the application of the coagulant to employ a temperature which is above the boiling point of the solvent, and is preferably below and near the boiling point of the coagulant.

If desired the filaments or other products produced by the above processes may be treated in any desired manner to increase their strength, or if desired further to modify their lustre. For example they may be treated according to the processes described in U. S. Patent No. 1,709,470,

or British Patent No. 323,790 or British Patent The filaments or other products uously with the spinning process or continuously therewith and with or without the application a of suitable solvents or swelling agents. If desired a solvent or swelling agent may even be incorporated in the precipitant applied to the filaments, and especially solvents or swelling agents of lower volatility than the precipitant itself, for example diacetone alcohol, ethyl lactate, diethyl tartrate, lactic acid, and the mono or di-ethers of olefine or poly-olefine glycols, in-

cluding dioxane, or esters of the monoethers. As a further modification such a relatively high boiling solvent may be incorporated in the spinning solution or may be applied to the filaments subsequent to the application of the precipitant.

Here again the volatility of the liquid applied may be such that it is substantially or completely eliminated from the filaments or other products during their drying.

As has already been indicated the invention 3 ill) is applicable to the production of filaments, threads or the like from any spinning solutions capable of being spun by dry spinning methods. Such spinning solutions may if desired contain inorganic or organic substances adapted to reduce or modify the lustre of the filaments, for example barium sulphate, zinc oxide, titanium oxide or the like, as described in British Patents Nos. 338,490 and 341,897, or the various organic substances specified in British Patents Nos. 346,678, 346,793 and 343,949. The term precipitant employed in the description and hereinafter in the claims is to be understood as meaning a substance, for example toluene, which effects precipitation of a cellulose derivative from its solution by reducing the solvent power of the solvent medium, and not a substance such as air which effects setting by promoting evaporation of solvent.

The following examples illustrate the invention but are not to be considered as limiting it in any way:-

Example 1 A 25% solution of cellulose acetate in a mixture of 95 parts of acetone to parts of water is spun according to dry spinning methods into a cell in which the heating arrangements are such that in the region of the nozzle the air temperature is of the order of Gil-65 C., while at a point some distance below the nozzle, and preferably about a foot below, the air temperature is about 80-90' C. This high degree of heating may be obtained by concentrating a bank of heating pipes in the desired position in the cell, or by employing a tubular structure at the desired height in the cell, preferably itself carrying a heating device, so that the whole of the evaporative medium is caused to pass through this relatively small area of the cross-section of the cell. Below this special heating means the heating arrangements are those normally employed in the dry spinning appartus. The nozzle is sprayed by means of a suitable atomizer with a petroleum fraction boiling at 90-l00 C. In this way the filaments become covered with the liquid petroleum fraction. Preferably prior to atomizing the petroleum fraction is suitably heated so as to avoid an undue cooling in the neighbour-- hood of the jet.

Example 2 A dry spinning apparatus is set up exactly as described in Example 1 with the exception that, instead of employing an atomizer, liquid coagulant is fed directly to the outer surface of the nozzle iself by means of the apparatus described with reference to Figures 1, 2, 3, 4 or 7 of British Patent No. 371,360. Conveniently in this case toluene or the above mentioned petroleum fraction may be employed. In the case of using toluene the very hot zone of the spinning cell may be maintained at a temperature of 95-105 C., while in the case of the petroleum fraction a temperature of 80-90 C. is maintained as before.

Example 3 The arrangements are similar to those described in Examples 1 and 2 with the exception that in order to produce the rapid evaporation of the solvent from the filaments after application to the coagulant a stream of air heated to the appropriate temperature, for example 90-100 C., is directed on to the filaments at an intermediate point in the cell, for example one foot below the nozzle.

Example 4 Instead of employing downward spinning as described in Example 2 above upward spinning is employed, and the coagulant is applied by means of the apparatus described with reference to Figures 5 and 6 of British Patent No. 371,360. By employing an upward current of air in the spinning cell the maintenance of the different heating zones in the spinning cell is facilitated.

Examples of apparatus which may be employed in carrying out the process according to the present invention are shown in the accompanying drawing, but it is to be clearly understood that they are given purely by way of illustration and do not limit the invention in any way. On the drawing,

Figure 1 shows diagrammatically one form of device for carrying out my invention, and

Figure 2 shows another form of device for carrying out my invention.

In the apparatus shown in Figure l, a bundle of filaments 4 are extruded through a suitable nozzle 3 connected to a candle filter 2 and enclosed in a cell I. A suitable precipitant is sprayed on the filaments in the very early stages of their formation from a ring-shaped perforated member 5, and the bundle of filaments after application of the precipitant in this manner pass through a cylindrical member l9 heated by steam pipes 6. Below this member or formed integral with it is a cone-shaped shield l. Evaporative medium introduced at I2 and withdrawn through the pipe 13 is thus collected by the cone-shaped member I and caused to pass through the heated funnel 6, thus effecting rapid evaporation of solvent from the bundle of filaments 4. When the filament bundle 4 reaches the bottom of the cell it is taken round the guide 8 and draw-roller 9 and then passes through the guide 10 to a cap spinning apparatus II. If desired the heating coils 6 and/or the shield I may be omitted.

' Figure 2 shows a portion of another form of apparatus which may be employed in accordance with the present invention. The lower portion 14 of the jet 3 has a hemispherical shape, and is surrounded by a cup-shaped member l9, containing precipitant, which is notched at intervals around its circumference at points I! so as to allow the liquid contained in it to flow down over the surface of the jet l4 and form a film through which the bundle of filaments 4 passes immediately on issuing from the jet orifices. The bundle of filaments then passes through a cylindrical member l5 attached to the walls of the spinning cell by brackets I8, where rapid evaporation of the solvent is produced by the evaporative medium.

What I claim and desire to secure by Letters Patent is:

1. The manufacture of hollow or voluminous filaments or the likefrom solutions of organic derivatives of cellulose, comprising applying a precipitant to the materials at an early stage of their drying and subsequently producing a rapid evaporation of solvent by employing a tempera ture above the boiling point of the solvent and below the boiling point of the precipitant.

2. The manufacture of hollow or voluminous filaments or the like from solutions of cellulose acetate, comprising applying a precipitant to the materials at an early stage of their drying and subsequently producing a rapid evaporation of solvent by employing a temperature above the boiling point of solvent and below the boiling point of the precipitate.

3. Process for the manufacture of filaments, threads and like products by dry spinning solutions of cellulose esters or ethers, comprising applying a precipitant to the extruded materials at an early stage of their drying and subsequently inducing a rapid evaporation of the solvent of the spinning solution from the materials so that hollow or voluminous products are obtained.

4. Process for the manufacture of filaments, threads and like products by dry spinning solutions of cellulose acetate, comprising applying to the extruded materials at an early stage of their drying a precipitant having a lower volatility under the spinning conditions than has the solvent of the spinning solution and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

5. Process for the manufacture of filaments, threads and like products by dry spinning solutions of acetone-soluble cellulose acetate, comprising applying to the extruded materials at an early stage of their drying a hydrocarbon precipitant having a lower volatility under the spinning conditions than has the solvent of the spinning solution and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

6. Process for the manufacture of filaments,

. threads and like products by dry spinning solutions of acetone-soluble cellulose acetate, comprising applying to the extruded materials at an early stage of their drying an aromatic hydrocarbon containing at most eight carbon atoms, the solvent of the spinning solution being more volatile than said hydrocarbon under the spinning conditions, and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

7. Process for the manufacture of filaments, threads and like products by dry spinning solutions of acetone-soluble cellulose acetate, comprising applying to the extruded materials at an early stage of their drying a petroleum fraction boiling between 60 and 120 C., the solvent of the spinning solution being more volatile than said petroleum fraction under the spinning conditions, and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

8. Process for the manufacture of filaments, threads and like products by dry spinning solutions of organic derivatives of cellulose, comprising applying to the extruded materials immediately after their extrusion, a precipitant having a lower volatility under the spinning conditions than has the solvent of the spinning solution and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

9. Process for the manufacture of filaments, threads and like products by dry spinning solutions of cellulose acetate comprising applying to the extruded materials immediately after their extrusion a precipitant having a lower volatility under the spinning conditions than has the solvent of the spinning solution and subsequently subjecting the materials to a temperature above the boiling point of the solvent to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

10. Process according to claim 9 wherein the precipitant is applied to the surface of the nozzle.

11. Process for the manufacture of filaments, threads and like products by dry spinning solutions of cellulose acetate comprising applying to the extruded materials immediately after their extrusion a precipitant in the liquid state, said precipitant having a lower volatility under the spinning conditions than has the solvent of the spinning solution and subsequently passing the materials through a heated zone at a temperature above the boiling point of the solvent and below the boiling point of the precipitant to induce a rapid evaporation of the solvent from the materials so that hollow or voluminous products are obtained.

HENRY DREYFUS.

CERTIFICATE OF CORRECTION.

Patent No 2,032,565. March 3, 1956.

HENRY DREYFUS.

It is hereby certified that error appears in the printed specification of Page 2, first the above numbered patent requiring correction as follows: column, line 50, for "or" read of; page 4, first column, line 5 claim 2., for

preoipitate read precipitant; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the ease in the Patent Office.

Signed and sealed this 28th day of April, A. D. 1956.

Leslie Frazer Acting Commissioner of Patents.

(Seal) 

